In the past year, drone warfare in Ukraine has undergone a chilling transformation.

In the past year, drone warfare in Ukraine has undergone a chilling transformation.: Most drones require a human pilot. But some new Ukrainian drones, once locked on a target, can use A.I. to chase and strike it — with no further human involvement.This is the story of how the battlefield became the birthplace of a powerful new weapon. By C.J. Chivers This story was reported over